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Tuesday, March 27, 2012

Study shows birds are slowly adjusting to climate change

ALBANY, N.Y.—A new study based on the National Audubon Society's North American Christmas Bird Count finds birds have taken decades to adjust their ranges northward in response to warming winters.

Frank La Sorte, a post-doctoral researcher at the Cornell Lab of Ornithology in Ithaca, was lead author of the study published online this month by the Journal of Animal Ecology. He said animals adjust to rising minimum winter temperatures by shifting their ranges northward. Since birds are highly mobile and migrate north and south with the changing seasons, they're better able to shift their ranges than less-mobile, non-migrating species, like amphibians.

AP photo

But the study of 59 bird species found it's not all that easy or quick. And some birds are better equipped to follow the changing climate than others.

Take black vultures. While the minimum winter temperature increased from 1975 to 2009, it took black vultures 35 years to catch up with the trend. Over that time, they have spread northward as far as Massachusetts, where winters now are similar to Baltimore's in 1975.

On the other hand, the endangered red-cockaded woodpecker hasn't moved at all. La Sorte said that could be because they have such specialized habitat needs, found only in the sandy longleaf pine forests of 11 southern states. "It might be good to go in and look at how well they're coping" with the rising temperature, La Sorte said Tuesday in an interview. "It depends on their physiological tolerance, and changes in the prey base."